Narrow band transceiver

Abstract

The data transmitted from a first station is transmitted at a first data rate. The data transmitted from a second station is transmitted at a second data rate. The second data rate is lower than the first data rate. In view of both the difference in data rates and the synchronization between radio stations, a separate synchronization word is not required to be sent from the second station to the first station on the uplink portion; instead, and because the uplink slots of a given frame are synchronized between transceiving stations, the start of the uplink payload slot can comprise signalling information which simply acts to signify the start of transmission of uplink data from the second station.

Description

CROSS REFERENCE TO RELATED APPLICATIONS[0001]This patent application is a Continuation of International Patent Application No. PCT / GB2007 / 004596 filed on Nov. 30, 2007 and entitled “NARROW BAND TRANSCEIVER”, the contents and teachings of which are hereby incorporated by reference in their entirety.FIELD OF THE INVENTION[0002]The present invention relates to a system for and method of digital communications, and is particularly, but not exclusively, suited to transceiving data at low data rates.BACKGROUND OF THE INVENTION[0003]The majority of point-to-multipoint radio communications systems operate at relatively high bandwidths, due to the high data rates and real-time requirements associated with data receipt and transmission. It would be attractive to operate at low bandwidths for applications having less stringent data rate requirements because of the commensurate advantages in relation to range and reduction in power requirements. However, low bandwidth systems can incur signific...

AI Technical Summary

Benefits of technology

This approach results in a lower-cost, efficient narrowband transmission system suitable for multiple remote stations, achieving approximately ¼ bit timing accuracy and eliminating the need for time-domain identification of uplink transmissions, thus reducing processing overhead and costs.

Problems solved by technology

The majority of point-to-multipoint radio communications systems operate at relatively high bandwidths, due to the high data rates and real-time requirements associated with data receipt and transmission.

However, low bandwidth systems can incur significant frequency lock problems due to the fact that the frequency error between the transmitter and the receiver is much greater than the signal bandwidth; the identification of the frequency error typically involves use of high accuracy components, which equates to a significant overhead in terms of costs, and to a commensurate limitation in the use of low bandwidth systems.

Typically this involves providing the base station with many sliding detectors, which are expensive in terms of computational requirements, and, for a large number of remote stations, can become prohibitively costly.

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